The present invention is directed to power transmissions and particularly transmissions associated with chain saws.
Chain saws have been developed as a light and powerful means for cutting timber and the like. The engines developed in association with these saws have been found to be of great utility in other areas because of their light and powerful nature. In spite of the advantages of a chain saw engine, one major disadvantage is that the saw is preferably operated in a limited range of orientations. There are two limitations on the attitude which may be taken by such chain saw motors. First, as chain saw driven devices tend to be hand-held rather than fixed, certain limitations on the ability of an individual to hold the saw must be considered. Second, the engine fuel system is frequently incapable of operating at certain attitudes because of fuel leakage, engine starvation or the like.
A disadvantage of any portable engine device is that it is generally expensive to manufacture. Consequently, to have a range of power tools available with adaptable power drives, a substantial investment in engines or drive couplings has been required. Thus, versatility and expense has proven to be a major detriment to the widespread purchase and use of lightweight, sophisticated, portable equipment.